Touch device and method for providing tactile feedback

ABSTRACT

A touch device includes a touch panel and a vibration device to provide tactile feedback to a user to locate a key on a display of the touch panel. A processor generates a drive signal to the vibration device when the position on the display touched by a finger or stylus corresponds to a location of a key on the display. The vibration device causes the display to vibrate in response to the drive signal to provide a tactile key location indication to the user while the key is touched.

BACKGROUND OF THE INVENTION

Manufacturers of hand-held and/or portable electronic devices, such aslaptop computers, personal digital assistants (PDA), wireline orwireless telephones, video games and other similar electronic devices,are continually striving to improve customer satisfaction with the usageof input devices, while still fitting the input devices within the formfactor of the electronic device. In order to provide common features,such as text messaging, calendar, games, phone book and web access,electronic devices typically include both a display and an input device.The display provides a graphical user interface to the customer tofacilitate access to the features. The input device enables selectionand implementation of the features (e.g., entering text, controllingcursor position and selecting or “clicking” on features). However, asthe size of electronic devices shrinks, the available area on theelectronic devices for both a display and an input device becomeslimited.

Recently, touch screens have been introduced to the laptop and hand helddevice industries to reduce the area needed for a display and inputdevice by combining input device functionality with a graphical userinterface. For example, touch screens typically include asoftware-defined keypad (“soft keypad”) displayed on the touch screenand a touch sensing mechanism for detecting when the touch screen istouched by a finger or stylus to input a key function. Exemplary touchsensing mechanisms include analog resistive, infrared, acoustic,capacitive or electromagnetic inductive sensors. Effective operation ofa touch screen requires visual feedback to the user to locate and selectmenu items and other software-defined keys on the touch screen. However,for some users and in some situations, visual feedback may not besufficient to determine that a key has been selected.

One solution for providing improved touch screen feedback is describedin U.S. Pat. No. 5,977,867 to Blouin. In the Blouin patent, a vibratoris attached to the touch screen to provide a tactile vibrating sensationto the user when a key on the touch screen is selected. The vibratorvibrates for a time that is long enough for the user to feel thesensation, but short enough to terminate before the next key touch.

However, the Blouin touch screen design still requires visual feedbackto the user to locate the key on the touch screen prior to touching thekey. In some situations, it is desirable for the user to be able tolocate keys without looking at the touch screen. For example, whendriving, a user may prefer to locate and select a menu item or locateand dial numbers on a software keypad using only tactile feedback inorder to maintain visual contact with the road. As another example, avision-impaired user may be unable to operate a touch screen having keylocations without tactile feedback. There is therefore a need for atactile feedback mechanism to assist a user in locating keys on a touchscreen.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a touch device including atouch panel and a vibration device for providing tactile feedback to auser to locate a key on a display of the touch panel. The displaydisplays keys constituting a soft keypad. The touch panel is operableproduce a position signal indicative of a position on the touch paneltouched by a user-controlled object. A processor is operable in responseto the position signal to generate a drive signal when the position onthe display corresponds to a key location of one of the keys on the softkeypad. The vibration device causes the display to vibrate in responseto the drive signal while the position corresponds to the key locationto provide a tactile key location indication to the user.

In one embodiment, the display is planar and the vibration of thedisplay is parallel to the plane of the display. In a furtherembodiment, the touch panel includes a housing in which the display iscompliantly mounted and the vibration device includes a moveable portionthat together with the display constitutes a mechanical assembly havinga resonant frequency. The processor drives the moveable portion at afrequency equal to the resonant frequency of the mechanical assembly.

In another embodiment, the processor is additionally operable to detectdamping of the vibration by the user-controlled device touching thedisplay, and, in response to detecting damping, to generate a clickindicate signal indicative of a click event performed by theuser-controlled object on the key at the key location corresponding tothe position on display.

In a further embodiment, the processor is operable to interrupt thedrive signal in response to the click indicate signal to cause thevibration device to interrupt the vibration of the display. In yet afurther embodiment, the touch device further includes anelectro-acoustic transducer operable in response to the click indicatesignal to produce an audible click indication to the user. In one aspectof the invention, the electro-acoustic transducer is operable to drivethe display in a direction orthogonal to the plane of the display toproduce the audible click indication.

Embodiments of the present invention further provide a method forproviding tactile feedback to a user of a touch device. The methodincludes receiving a position signal indicative of a position on adisplay of the touch device touched by a user-controlled object, andcomparing the position to key locations of keys displayed on thedisplay. While the position corresponds to one of the key locations, themethod further includes causing the display to vibrate to provide atactile key location indication to the user.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed invention will be described with reference to theaccompanying drawings, which show important sample embodiments of theinvention and which are incorporated in the specification hereof byreference, wherein:

FIG. 1 is a front view of an exemplary tactile feedback touch device, inaccordance with embodiments of the present invention;

FIG. 2 is a cross-sectional view along the section line 2-2 of theexemplary tactile feedback touch device shown in FIG. 1, in accordancewith embodiments of the present invention;

FIG. 3 is a block diagram illustrating an exemplary touch device capableof providing tactile feedback, in accordance with embodiments of thepresent invention; and

FIG. 4 is a flow chart illustrating an exemplary process for providingtactile feedback to a user of a touch device, in accordance withembodiments of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 is a front view of an exemplary touch device 150 for providingtactile feedback, in accordance with embodiments of the presentinvention. The touch device 150 can be included in any type ofelectronic device. For example, electronic devices include wireless(cellular) telephones, personal digital assistants (PDAs), laptopcomputers, notebooks, hand-held video game devices, portable musicplayers or other similar electronic devices. The touch device 150includes a touch panel 10 and a vibration device 50.

The touch panel 10 shown in FIG. 1 includes a touch screen sensor 40laid over a liquid crystal display (LCD) 20. The touch screen sensor 40includes a linear array of infrared (IR) emitters located on twoorthogonal sides of the touch screen sensor 40. The IR emitters form amatrix in the x-y plane of IR beams 45 across the display 20. IRdetectors for detecting the IR beams 45 are arrayed along the sides ofthe touch screen sensor 40 opposite the IR emitters. Entry of auser-controlled object 70, such as a finger, pen, pointer or otherstylus, into the matrix of IR beams 45 is detected when one or more IRbeams 45 are broken and, therefore, no longer sensed by theircorresponding IR detectors. The position (e.g., x, y coordinates) of theuser-controlled object 70 in the touch screen sensor 40 is determinedfrom the positions (e.g., x coordinates and y coordinates) of the brokenIR beams 45 on the touch screen sensor 40. Although the touch screensensor 40 shown in FIG. 1 is an IR touch screen sensor, in otherembodiments, the touch screen sensor 40 is an analog resistive,acoustic, capacitive, ultrasonic or electromagnetic inductive touchscreen sensor.

The display 20 is a configurable display capable of displaying one ormore keys 65 constituting a software-defined (“soft”) keypad 60. Thesize, shape, location and number of keys 65 are dependent upon theapplication and may be limited by the size of the display, the size ofthe user-controlled object 70 and the resolution of the touch screensensor 40. For example, in one embodiment, as shown in FIG. 1, thekeypad 60 is a numeric keypad 60 containing numeric keys 65 arranged ason a conventional telephone. In another embodiment, to assist users inidentifying keys 65, each key 65 is a different size and/or shape (e.g.,round, oval, square, rectangular, long, tall, thin, thick, etc.).

The vibration device 50 is operable to produce vibrations 55. Vibrations55 cause the display 20 to vibrate to provide a tactile key locationindication to the user, thereby enabling the user to locate a key 65 onthe display 20. As shown in FIG. 1, the vibration device 50 includes astatic portion 52 and a moveable portion 54. The static portion 52 ofthe vibration device 50 is coupled to the housing 30, while the moveableportion 54 of the vibration device 50 is moveable within the housing 30and mechanically coupled to the display 20. The static portion 52 of thevibration device 50 drives the movable portion 54 of the vibrationdevice 50 at a frequency corresponding to a resonant frequency of amechanical assembly 25 formed of a combination of the display 20 and themoveable portion 54 of the vibration device 50. Although the vibrationdevice 50 is shown and described herein as having a moveable portion 54and a static portion 52, the vibration device 50 may include any type ofdevice capable of casing the display 20 to vibrate with a linear orcircular motion.

For example, in one embodiment, the vibration device 50 includes arotary motor with an eccentric weight. The rotary motor is mechanicallycoupled to the display 20. The rotary motor causes the weight to rotatein plane parallel to the plane of the display 20 (i.e., x-y plane) toproduce circular vibrations 55 of the display 20. Thus, as the motordrives the weight in a direction away from the display 20, the motion ofthe weight causes the display 20 to move in the opposite direction(i.e., further away from the motor). Likewise, as the motor drives theweight in a direction towards the display 20, the motion of the weightcauses the display 20 to move towards the motor. The rotary motorincreases the rotational speed of the weight until the rotational speedreaches the resonant frequency of the mechanical assembly 25. Forexample, the vibration device 50 can produce vibrations 55 at a resonantvibration frequency between 100-200 Hz. By vibrating the display 20 onlyin the x-y plane, there is no motion of the display 20 in thez-direction. Such motion of the large planar surface of the display 20in the z-direction would generate audible acoustic energy.

In another exemplary embodiment, the vibration device 50 includes alinear motor comprising a permanent magnet and a voice coil located in amagnetic field of the permanent magnet. In one embodiment, the permanentmagnet constitutes the static portion 52 and the voice coil constitutesthe movable portion 54 of the vibration device 50. In an alternativeembodiment, the voice coil constitutes the static portion 52 and thepermanent magnet constitutes the movable portion 54 of the vibrationdevice 50. The static portion 52 of the vibration device is coupled tothe housing 30. In an example in which the permanent magnet constitutesthe static portion 52 of the vibration device, an alternating drivesignal applied to the voice coil drives the voice coil back and forth inthe magnetic field in a direction parallel to the plane of the display20 to produce linear vibrations 55 of the display 20. Once the frequencyof the vibrations 55 reaches the resonant frequency of the mechanicalassembly 25, the current needed to apply the alternating drive signal isreduced.

In yet another exemplary embodiment, the vibration device 50 is operableto modulate the amplitude of the vibration 55 dependent on the positionof the user-controlled object 70 relative to the position of a key 65.In embodiments using a linear motor, the vibration amplitude ismodulated by modulating the current of the drive signal applied to thevoice coil. In embodiments using a rotary motor, the vibration amplitudeis modulated by modulating the rotational speed of the rotary motorrelative to the resonant frequency of mechanical assembly 25. Modulatingthe amplitude of the vibrations 55 produces a three-dimensional tactilekey location indication that defines the contour of a key 65 sensed bythe user. For example, as the user moves the user-controlled object 70across a key 65, the amplitude of the vibrations 55 increase as theuser-controlled object 70 approaches the center of the key 65 to givethe impression that the key has a rounded edge instead of a square edge.As another example, as the user moves the user-controlled object 70across a key 65, the amplitude of the vibrations 55 decrease as theuser-controlled object 70 approaches the center of the key 65 to givethe impression of the key 65 having a concave keycap. As a furtherexample, amplitude variations can be used to define more complicatedkeys, such as rocker switches and 4-way navigation devices.

In a further embodiment, the vibration device 50 includes two or morevibration devices attached to different sides of the display 20. Inanother embodiment, the silent ring vibrator of the electronic device(e.g., cell phone or PDA) incorporating the touch device 150 is used asthe vibration device. However, silent ring vibrators available todaytypically cause the entire electronic device (and not just the display20) to vibrate, which may not be desirable in some applications.

The display 20 is compliantly mounted in a housing 30 via a flexiblesurround 90. In one embodiment, the flexible surround 90 is formed of amaterial, such as elastomer or rubber, and has a mechanical resonance atthe frequency of the vibration 55. For example, the thickness, type andshape of the material forming the flexible surround 90 can be selectedto produce the mechanical resonance of the flexible surround 90 at theresonant frequency of the mechanical assembly 25. At frequencies otherthan the resonant frequency of the mechanical assembly 25, the flexiblesurround 90 tightly couples the display 20 to the housing 30. However,at the resonant frequency of the mechanical assembly 25, the resonanceof the flexible surround 90 decouples the display 20 from the housing30. This reduces the power that the vibration device 50 needs to causethe display 20 to vibrate at the resonant frequency. In addition, theflexible surround 90 at resonance presents a high mechanical impedanceto the housing 30 to minimize acoustic coupling between the display 20and the housing 30, thereby minimizing vibrations in the housing 30.

In another embodiment, instead of using a mechanically-resonant flexiblesurround 90, the display 20 and the static portion 52 of the vibrationdevice 50 are each compliantly coupled to the housing 30 to providesubstantially equivalent acoustical coupling between the housing 30 andthe display 20 and between the housing 30 and the vibration device 50.In addition, the display 20 and the static portion 52 of vibrationdevice 50 vibrate in opposite directions, such that the net momentumcollectively applied to the housing 30 by the mechanical assembly 25 andthe vibration device 50 approaches zero. As a result of thesubstantially equivalent acoustical coupling, the vibrations 55 of thevibration device 50 cancel out the vibrations of the display 20, therebyminimizing the vibrations of the housing 30.

In a further embodiment, the vibration device 50 includes two or morevibration devices attached to different sides of the display 20. Inanother embodiment, the silent ring vibrator of the electronic device(e.g., cell phone or PDA) incorporating the touch device 150 is used asthe vibration device. However, silent ring vibrators available todaytypically cause the entire electronic device (and not just the display20) to vibrate, which may not be desirable in some applications.

The display 20 is compliantly mounted in a housing 30 via a flexiblesurround 90. In one embodiment, the flexible surround 90 is formed of amaterial, such as elastomer or rubber, that is resonant at the frequencyof the vibration 55. For example, the thickness, type and shape of thematerial forming the flexible surround 90 can be selected to produce amechanical resonance of the flexible surround 90 at the resonantfrequency of the mechanical assembly 25. At frequencies other than theresonant frequency of the mechanical assembly 25, the flexible surround90 tightly couples the display 20 to the housing 30. However, at theresonant frequency of the mechanical assembly 25, the resonance of theflexible surround 90 decouples the display 20 from the housing 30. Thisreduces the power that the vibration device 50 needs to cause thedisplay 20 to vibrate. In addition, the flexible surround 90 atresonance presents a high impedance to the housing 30 to minimizeacoustic coupling between the display 20 and the housing 30, therebyminimizing vibrations in the housing 30.

In another embodiment, instead of using a mechanically-resonant flexiblesurround 90, the display 20 and the static portion 52 of the vibrationdevice 50 are each compliantly coupled to the housing 30 to providesubstantially equivalent acoustical coupling between the housing 30 andthe display 20 and between the housing 30 and the vibration device 50.In addition, the display 20 and vibration device 50 are configured tovibrate in opposite directions, such that the net momentum collectivelyapplied to the housing 30 by the mechanical assembly 25 and thevibration device 50 approaches zero. As a result of the substantiallyequivalent acoustical coupling, the vibrations 55 of the vibrationdevice 50 cancel out the vibrations of the display 20, therebyminimizing the vibrations of the housing 30.

In operation, when the user touches the display 20 at a positioncorresponding to the location of a key 65 on the soft keypad 60 with theuser-controlled object 70 (e.g., finger or stylus), the vibration device50 causes the display 20 to vibrate to provide a tactile key locationindication to the user while that the user-controlled object ispositioned over the key 65. As can be seen in FIG. 1, each key 65occupies an area on the display 20 over which one or more IR beams 45are directed in the x-y plane. The user initially positions theuser-controlled object 70 in the matrix of IR beams 45 over a region 75of the display 20. The region 75 on the display 20 occupied by theuser-controlled object 70 is compared to each key area to determine ifan overlap exists between the region 75 occupied by the user-controlledobject and one of the key areas. If the region 75 of the display 20occupied by the user-controlled object 70 is devoid of keys 65 (i.e.,there is no overlap between the occupied region 75 and any key area),the vibration device is not activated. However, as the user-controlledobject 70 is moved across the display 20 from a region devoid of keys 65towards one of the key areas (i.e., when the occupied region 75 overlapsat least a portion of a key area), the vibration device 50 is activatedto produce the vibration 55 of the display 20.

FIG. 2 is a cross-sectional view of the exemplary tactile feedback touchdevice 150, in accordance with embodiments of the present invention. Ascan be seen in FIG. 2, the display 20 is compliantly mounted in theresonant housing 30 by the flexible surround 90, and the touch screensensor 40 is positioned above the housing 30. The touch screen sensor 40includes IR emitters 42 located on two orthogonal sides of the touchscreen sensor 40. The IR emitters 42 form a matrix in the x-y plane ofIR beams across the display 20. IR detectors 43 for detecting the IRbeams are arrayed along the sides of the touch screen sensor 40 oppositethe IR emitters 42.

The static portion 52 and moveable portion 54 of the vibration device 50are more clearly seen in FIG. 2. The static portion 52 of the vibrationdevice 50 is fixed to the housing 30, while the moveable portion 54 ofthe vibration device 50 is moveable within the housing 30 andmechanically coupled to the display 20. The static portion 54 drives themoveable portion 52 to produce vibrations 55 of the mechanical assembly25 (i.e., moveable portion 54 in combination with the display 20) in adirection parallel to the plane (x-y plane) of the display 20 when theuser touches the display 20 at a position corresponding to a location ofa key on the soft keypad displayed on the display 20 with auser-controlled object (e.g., finger or stylus). This provides a tactilekey location indication to the user while the user-controlled object ispositioned over the key.

As described above, once the frequency of the vibration 55 reaches theresonant frequency of the mechanical assembly 25, the drive signalneeded to maintain the vibration 55 may be able to be reduced. However,when the user emulates pressing a key by applying a force on the display20 in a direction orthogonal to the plane of the display 20, acousticenergy absorbed by the user-controlled device damps the vibration. Thisdamping is used to indicate a click event performed by theuser-controlled object. As used herein, the term “click event” refers toa selection, execution or drag function as performed by a left button ofa conventional mouse. By way of example, but not limitation, clickevents include the single click function, the double click function andthe click and drag function of a conventional mouse.

In one embodiment, the vibration device 50 detects the amplitude of thevibrations 55, and therefore, a reduction in the amplitude caused bydamping the vibrations is used to indicate the click event. Inembodiments using a linear motor, the vibration device detects dampingas a result of an increase in the current needed to maintain theamplitude of the vibrations 55. As an example, a threshold level greaterthan the steady-state drive signal can be set for a click event. Whenthe steady-state drive signal increases to the threshold level, a clickevent is detected. As another example, in embodiments using a rotarymotor, damping can be detected through a servo-loop used to control thedrive signal frequency.

To indicate to the user that a click event has been detected, the touchpanel 10 or the electronic device incorporating the touch paneladditionally provides some type of acoustic or tactile feedback to theuser. In one embodiment, as shown in FIG. 2, the touch panel 10 furtherincludes an electro-acoustic transducer 80 under the display 20 forproducing an audible click indication to the user when a click event isdetected. In an exemplary embodiment, the electro-acoustic transducer 80drives the display 20 in a direction 85 (z-direction) orthogonal to theplane of the display 20 to produce the audible click indication. Inanother embodiment, the vibration device 50 is operable when a clickevent is detected to interrupt the vibration 55 of the display 20 for apredetermined time to provide a tactile click indication to the user. Ina further embodiment, the click indication, such as an audible beep,tone or click, is provided to the user using a conventional loudspeakerbuilt-in to the touch panel 10.

FIG. 3 is a block diagram illustrating an exemplary touch device 150capable of providing tactile feedback to a user, in accordance withembodiments of the present invention. The touch device 150 includes thetouch panel 10, the vibration device 50, a processor 100 and a memorydevice 110. The touch panel 10 includes a display 20 compliantly mountedin a housing 30 (as shown in FIGS. 1 and 2). The processor 100 incombination with the memory device 110 controls the operation of thevibration device 50.

The processor 100 is connected to receive from touch panel 10 a positionsignal 120 indicative of the position on the display 20 of auser-controlled object. The processor 100 compares the positionindicated by the position signal 120 to known key locations on thedisplay 20 to determine whether the position corresponds to one of theknown key locations. When the position does correspond to one of the keylocations, the processor 100 generates a drive signal 130 to initiatethe vibration of the touch panel 10. However, when the position does notcorrespond to one of the key locations, the processor 100 does notgenerate the drive signal 130 so that the display 20 does not begin tovibrate, or if already vibrating, stops vibrating.

For example, as described above in connection with FIG. 1, the positionon the display 20 of the touch panel 10 indicated by the position signal120 corresponds to a region on the display 20 occupied by theuser-controlled object, and each key location on the display 20corresponds to a key area on the display 20. The processor 100 isoperable to determine when an overlap exists between the region occupiedby the user-controlled object and one of the key areas. When theoccupied region is devoid of keys (i.e., there is no overlap between theoccupied region and any key area), the processor 100 does not activatethe vibration device 50, or if the vibration device 50 is alreadyactivated, the processor 100 deactivates the vibration device 50.However, when there is overlap between the occupied region and at leasta portion of one of the key areas, the processor 100 activates thevibration device 50 to produce the vibration of the display 20.

The processor 100 is further connected to measure the amplitude of thevibration 140 of the vibration device 50 and to adjust the level of thedrive signal 130 as necessary to maintain the amplitude of the vibrationof the display 20. For example, in one embodiment, the processor 100 isoperable to detect a click event performed by the user-controlled objectwhen the drive signal 130 increases to a level exceeding a thresholdlevel. In response to detecting a click event, the processor 100 isfurther operable to generate a click indicate signal 160. The clickindicate signal 160 causes the touch panel 10 to produce a clickindication, such as an audible click indication, to the user. Forexample, in embodiments in which the touch panel 10 includes aloudspeaker, the click indicate signal 160 causes the loudspeaker toproduce the audible click indication. In embodiments in which the clickindication is a tactile click indication provided by the vibrationdevice 50, the click indicate signal 160 interrupts the vibration of thedisplay 20 for a predetermined time. In a further embodiment, the clickindicate signal 160 is provided to a conventional built-in loudspeakerin the electronic device incorporating the touch device 150 to providean audible beep, tone or click to the user.

The processor 100 can be a microprocessor, microcontroller, programmablelogic device or any other processing device. The memory device 110 canbe any type of memory device for use on any type of electronic device.For example, the memory device 110 can be a flash ROM, EEPROM, ROM, RAMor any other type of storage device. In one embodiment, the memorydevice 110 stores software executable by the processor 100 to cause theprocessor 100 to generate the drive signal 130. For example, thesoftware can include an algorithm for comparing the position of theuser-controlled object, as indicated in the position signal 120, toknown key locations on the display 20 and generating the drive signal130 to initiate vibration of the vibration device 50. In anotherembodiment, the algorithm is stored in the processor 100, and the memorydevice 110 stores data used by the processor 100 during the vibrationcontrol process. For example, the memory device 110 can store the knownkey locations for comparison with the position of the user-controlledobject. As another example, the memory device 110 can store the signalthreshold level for use in detecting a click event.

FIG. 4 is a flow chart illustrating an exemplary process 400 forproviding tactile feedback to a user of a touch device, in accordancewith embodiments of the present invention. Initially, at block 410, aposition signal indicating a position on the display of a touch panel ofthe touch device touched by a user-controlled object is received. Atblock 420, the position indicated by the position signal is compared tokey locations of keys displayed on the display. At block 430, a decisionis made whether the indicated position corresponds to one of the keylocations. When the indicated position does not correspond to one of thekey locations, the process is repeated at block 410. However, when theindicated position does correspond to one of the key locations, at block440, the display is caused to vibrate to provide a tactile key locationindication to the user. At block 450, as long as the position continuesto correspond to the key location, at block 440, the display isvibrated. However, when the position no longer corresponds to the keylocation, at block 460, the vibration of the display is ceased.

The innovative concepts described in the present application can bemodified and varied over a wide rage of applications. Accordingly, thescope of patents subject matter should not be limited to any of thespecific exemplary teachings discussed, but is instead defined by thefollowing claims.

1-25. (canceled)
 26. A touch device for providing tactile feedback to auser, said touch device comprising: a touch panel comprising a displaydisplaying keys constituting a software-defined keypad, said touch paneloperable to produce a position signal indicative of a position on saiddisplay touched by a user-controlled object; a processor operable inresponse to said position signal to generate a drive signal when saidposition on said touch panel corresponds to the key location of one ofsaid keys on said soft keypad; and a vibration device operable inresponse to said drive signal to cause said display to vibrate whilesaid position corresponds to said key location to provide a tactile keylocation indication to the user; wherein the vibration device isactivated to produce vibration by the movement of the user-controlledobject from a region devoid of keys to a region that overlaps at least aportion of a key location.
 27. The touch device of claim 26, whereinsaid processor is additionally operable to detect damping of saidvibration by said user-controlled object touching said display, and, inresponse to said detecting, to generate a click indicate signalindicative of a click event performed by said user-controlled object onsaid one of said keys at said key location corresponding to saidposition on said display.
 28. The touch device of claim 27, furthercomprising: an electro-acoustic transducer operable in response to saidclick indicate signal to produce an audible click indication to theuser.
 29. The touch device of claim 28, wherein said electro-acoustictransducer is operable to drive said display in a direction orthogonalto the plane of said display to produce said audible click indication.30. The touch device of claim 27, wherein said processor is furtheroperable to interrupt said drive signal in response to said clickindicate signal to cause said vibration device to interrupt saidvibration.
 31. The touch device of claim 26, wherein said vibrationdevice is mechanically coupled to said touch panel.
 32. An electronicdevice comprising the touch device of claim 26 and a silent ringvibrator, wherein said silent ring vibrator is used as said vibrationdevice.
 33. The touch device of claim 26, wherein said display is planarand said vibration is parallel to the plane of said display.
 34. Thetouch device of claim 33, wherein: said touch device additionallycomprises a housing in which said display is compliantly mounted; saidvibration device comprises a movable portion, said movable portion andsaid display constituting a mechanical assembly having a resonantfrequency; and said processor is operable to drive said moveable portionat a frequency equal to said resonant frequency of said mechanicalassembly.
 35. The touch device of claim 34, wherein: said touch deviceadditionally comprises a flexible surround compliantly mounting saiddisplay in said housing; and said flexible surround has a resonantfrequency equal to that of said mechanical assembly.
 36. The touchdevice of claim 33, wherein: said vibration device additionallycomprises a static portion; said static portion of said vibration deviceand said display are each compliantly coupled to said housing; and saiddisplay and vibration device are configured to vibrate in oppositedirections such that the net momentum collectively applied to saidhousing by said mechanical assembly and said vibration device approacheszero.
 37. The touch device of claim 26, wherein said processor isfurther operable to modulate said drive signal dependent on saidposition of said user-controlled device relative to said key location toprovide a three-dimensional tactile key location indication to the user.38. The touch device of claim 26, wherein said touch panel comprises ananalog resistive sensor, infrared sensor, acoustic sensor, capacitivesensor, ultrasonic sensor or electromagnetic inductive sensor.
 39. Amethod for providing tactile feedback to a user of a touch devicecomprising a display, said method comprising: receiving a positionsignal indicative of a position on a touch panel comprising a displaydisplaying keys constituting a software-defined keypad, said displaytouched by a user-controlled object; comparing said position to keylocations of keys displayed on said display; and causing said display tovibrate while said position corresponds to one of said key locations toprovide a tactile key location indication to the user; wherein thevibration is activated to produce vibration by the movement of theuser-controlled object from a region devoid of keys to a region thatoverlaps at least a portion of a key location.
 40. The method of claim39, further comprising: detecting damping of said vibration caused bysaid user-controlled object touching said touch panel; and in responseto said detecting, identifying a click event performed on the one ofsaid keys at said key location corresponding to said position on saiddisplay.
 41. The method of claim 40, further comprising: in response tosaid identifying said click event, providing an audible click indicationto the user.
 42. The method of claim 41, wherein said providing saidaudible click indication comprises: driving said display in a directionorthogonal to the plane of said display to provide said audible clickindication.
 43. The method of claim 40, further comprising: in responseto said identifying said click event, interrupting said vibration ofsaid display.
 44. The method of claim 39, wherein said causing saiddisplay to vibrate further includes: causing said display to vibrateparallel to the plane of said display; said touch device additionallycomprises a housing in which said display is compliantly mounted; saiddisplay constitutes part of a mechanical assembly having a resonantfrequency; and causing said display to vibrate comprises driving saiddisplay at a frequency equal to said resonant frequency of saidmechanical assembly.
 45. The method of claim 39, wherein said causingsaid display to vibrate includes: in response to said position of saiduser-controlled device relative to said one of said key locations,modulating the amplitude with which said display vibrates to provide athree-dimensional tactile key location indication to the user.